A numerical study of the flow field in the vicinity of a bluff body with aspiration oriented to the flow

Aerosol samplers, which are widely used in environmental and industrial hygiene, generally operate by withdrawing air through an orifice in their surface. An understanding of the air flow around and into such bodies is important in understanding the samplers performance. Hence this work describes a numerical study of the flow field in the samplers vicinity. A three-dimensional spherical sampler is considered, although the results can be extended to other three-dimensional samplers. Using a complex variable method, the components of fluid velocity are determined and hence the flow behaviour is investigated. The region on the sampler surface, within which all the flow enters the sampling inlet, is studied in detail, using a numerical approach. An accurate description of this region is important for understanding the samplers performance. A simple expression is derived for the area of this region.